[libc++][test][NFC] Remove libcpp-no-concepts.

[Mordante]

Summary

This is no longer needed.

[Mordante]

I intend to land this if it passes the CI.

[Mordante]

The CI failure seems unrelated to this patch. I'll land it and keep an eye on the next scheduled CI build.

libcxx/test/libcxx/iterators/predef.iterators/reverse.iterators/bad_template_argument.verify.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17
-// UNSUPPORTED: libcpp-no-concepts
 
 // <iterator>
 
 // reverse_iterator
 
 #include <iterator>
 
 #include "test_iterators.h"
 
 int main(int, char**) {
   using BadIter = std::reverse_iterator<forward_iterator<int*>>;
   BadIter i; //expected-error-re@*:* {{static_assert failed{{.*}} "reverse_iterator<It> requires It to be a bidirectional iterator."}}
 
   return 0;
 }

libcxx/test/std/algorithms/alg.sorting/alg.min.max/ranges.min.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 // <algorithm>
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17
-// UNSUPPORTED: libcpp-no-concepts
 // UNSUPPORTED: libcpp-has-no-incomplete-ranges
 
 // template<class T, class Proj = identity,
 //          indirect_strict_weak_order<projected<const T*, Proj>> Comp = ranges::less>
 //   constexpr const T& ranges::min(const T& a, const T& b, Comp comp = {}, Proj proj = {});
 // template<copyable T, class Proj = identity,
 //          indirect_strict_weak_order<projected<const T*, Proj>> Comp = ranges::less>
 //   constexpr T ranges::min(initializer_list<T> r, Comp comp = {}, Proj proj = {});

libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/sfinae.compile.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17
-// UNSUPPORTED: libcpp-no-concepts
 
 // <iterator>
 //
 // reverse_iterator
 //
 // template <class Iterator1, class Iterator2>
 // constexpr bool                          // constexpr in C++17
 // operator==(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);

libcxx/test/std/iterators/predef.iterators/reverse.iterators/sized_sentinel.compile.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17
-// UNSUPPORTED: libcpp-no-concepts
 
 // reverse_iterator
 
 #include <iterator>
 
 #include "test_iterators.h"
 
 template<class T> concept HasMinus = requires (T t) { t - t; };